The present invention relates to a method of assembling a color developing apparatus provided in an electrophotographic copier, for example.
Some developing apparatuses of this type have a rotatable holding unit and a plurality of developing units arranged over the rotating direction of the holding unit.
Each of the plurality of developing units contains a different color toner and has a developing roller. These developing units are sequentially moved to the developing position by the rotation of the holding unit. An electrostatic latent image formed on a photoconductor is moved to the developing position by the rotation of the photoconductive element. A first color toner is supplied to the latent image by the rotation of the developing roller, and a first color toner image is formed. The toner image is transferred to an intermediate transfer unit, for example.
After the first color toner image is formed, the holding unit rotates, the developing unit is moved to the developing position, and a second color toner image is formed on the photoconductive element. The second color toner image is transferred over the first color toner image on the intermediate transfer unit. Toner images of the other colors are sequentially formed in the same manner, transferred over the toner image on the intermediate transfer unit, and a full-color image is formed and transferred to paper.
It is necessary for preferable development to set the developing roller and photoconductor parallel to one another.
Thus, in the prior art, a plurality of recesses is formed in the circumference of the side plates of the front and rear sides of a holding unit, over the circumferential direction, and a developing roller is mounted by fitting both ends of its center shaft into a recess.
A holding unit has to be made by press work when the material of its side plate is sheet metal, and by injection molding when the material is plastic. In either case, a precision mold must be used.
However, considering the precision of a producible mold, later press work and injection molding accuracy, it is difficult to make the recesses with the theoretically demanded positioning accuracy, and it becomes impossible to produce a good image.
Thus, clamping an optional concave support member to the circumference of a pair of side plates of a holding unit over its rotating direction by means of a plurality of screws, and fitting through a bearing both ends of the center shaft of a developing roller to the support members of the pair of side plates has been considered.
In this case, it is possible to position the concave support members by a jig, and it is also possible to ensure the positioning accuracy of the support members by increasing the positioning accuracy of the jig.
However, in the prior art, since all optional support members are positioned by a jig, it is possible to ensure the relative positioning accuracy of the jig and support members, but the positioning accuracy is lowered between the side plate and support members.
Thus, when the front and rear side plates are made in one body by connecting them through a shaft and a stay member and a developing roller is provided between these side plates, there arises a problem that a twist is generated before and after the holding unit and it becomes difficult to keep a developing roller and an image holding member parallel.